Acute necrotizing ulcerative gingivitis (ANUG) is a unique inflammatory periodontal disease characterized by sudden onset, aggressive soft tissue destruction and a possible correlation of onset to psychological stress. It is the only periodontal disease exhibiting early stage bacterial invasion of vital tissues. Albeit not common, the hightest incidence of ANUG occurs in young adults and can range form 2.2 percent to 6.7 percent. Although immunological mechanisms are implicated in the pathogenesis of inflamatory periodontal disease, most research has focused on chronic gingivitis, adult periodontitis and juvenile periodontitis. Comparatively little research effort has been directed towards defining ANUG disease mechanisms. The purpose of this study is to: (1) determine by immunohistochemical methods the distribution, density and phenotype of immunocompetent cells at different stages of the ANUG lesion, i.e., prodromal, mature and regressive stages; and (2) investigate the relationship between psychological stress in ANUG patients, as manifested by serum cortisol levels, and the competence of their peripheral blood polymorphonuclear leukocytes (PMNL) during chemotaxis and phagocytosis. Based on a defined combination of clinical symptoms, ANUG patients will be assigned to one of the three stages and will constitute the three study groups. Three control groups will be used; one free of gingival inflammation; one with chronic gingivitis; and the last being the prodromal ANUG patient using an adjacent area of inflammed gingiva but free of the ulceration and necrosis associated with ANUG. Biopsies of a gingival papilla and blood samples will be obtained from each patient. Using an expanded panel of monoclonal antibodies and the avidin- biotin immunoperoxidase histochemical staining technique, a histometric determination of immunophenotypes, densities and distributions will be accomplished for each of the six groups of patients. Furthermore, serum cortisol levels will be determined for each patient via radioimmuno-assay. These levels will be correlated to competence of the patient's PMNL during chemotaxis and phagocytosis. The latter assays will be performed using the nitroblue tetrazolium and Boyden blind will chamber techniques. Statistical comparisons between groups will be accomplished by analysis of variance to determine what effect the stage of disease has upon the various parameters, i.e, immune phenotype, densities, phagocytosis, chemotaxis and serum cortisol levels.